Theoretical Analysis And Finite Element Research On The Outer Angle Steel Reinforced Casing Member

With the increasing complexity of the space grid structure,the safety control of the structure during construction is becoming more and more important,especially the stability of key compression members.Improper control can easily cause the continuity of the structure to collapse.As one of the limiting instability technologies,casing reinforcement technology is commonly used to control the stability of the member under pressure,but the inconvenience of construction has limited its promotion in the field of member reinforcement.Based on this,this paper proposes a new type of casing member,namely,reinforced casing member with angle steel,which is simple and easy to operate,and can be disassembled after the installation of the grid.For this casing member,the main research contents of this article are as follows:With the help of the finite element software ABAQUS,a simplified model of the casing member was established,and compared with the test results,it was found that the load-displacement curve and the failure mode of the two were in good agreement,and the correctness of the finite element model was verified.Therefore,the finite element model can be used for subsequent parameter analysis of casing components.The two failure modes that can occur in the casing member are overall instability failure and instability failure at the end of the core extension.We conduct theoretical analysis separately and derive the calculation formula of its bearing capacity.For the whole unstable failure member,the calculation formula of its elastic buckling bearing capacity is obtained.The equivalent stiffness method is used to obtain the equivalent stiffness of the member with an extended section in the core.By introducing the coefficients ?1 and ?2,the ultimate stable bearing capacity of the casing member is obtained.For the instability member at the end of the core extension,we establish a mechanical analysis model of point contact between the core and the outer constraint member to obtain the expressions of the squeezing force at the end of the core and the outer constraint member,the deflection of the extension segment and the end bending moment,and establish the end failure criterion.The finite element model verified by experiments was used to analyze the parameters,and the influence of parameters such as the length of the core extension,the core length,the thickness of the inner and outer tubes,the number of outer hoops,and the cross-sectional size on the bearing capacity and failure mode of the member was discussed,which proves that the method has good mechanical performance.Based on the parameter analysis,the failure mechanisms of the two failure modes are summarized,and the classification limits of the two failure modes of ?60 rods are fitted.Combined with the finite element analysis data,the expression of the coefficient?1?2 in the calculation formula of the bearing capacity of the casing member when the overall instability failure occurs is determined,and the calculation formula of the stable bearing capacity is obtained,which can be used to guide the engineering design.For the instability members at the end of the core extension,the theoretical analysis of the end compression force,end bending moment and ultimate bearing capacity is in good agreement with the finite element results.The theoretical formula has high accuracy and the result is safe.Therefore,it can be used in the design check calculation.